The present invention relates to a process for producing 1,4-naphthoquinone. More particularly, it relates to an improved process for producing 1,4-naphthoquinone by a vapor phase catalytic oxidation of napthalene comprising passing naphthalene and a molecular oxygen-containing gas through a fixed catalyst bed of a vanadium oxide type catalyst. 2. DESCRIPTION OF THE PRIOR ARTS
It has been known to use a catalyst obtained by supporting catalytic components of (1) vanadium oxide, (2) an alkali metal sulfate and (3) an alkali metal pyrosulfate on a carrier such as silicon oxide as an improved catalyst in a process for producing 1,4-naphthoquinone. Thus, a satisfactory result has not been obtained in view of a conversion of naphthalene, an yield of 1,4-naphthoquinone and a space time yield. The reason is as follows. 1,4-Naphthoquinone is an intermediate as a preliminary oxidized product of naphthalene. When a catalyst for imparting high conversion of naphthalene is used, a conversion of 1,4-naphthoquinone to phthalic anhydride as a sequential reaction is also high. In view of industrial production, it is desired to obtain a high yield of 1,4-naphthoquinone and a smaller amount of the unreacted naphthalene.